Heretofore these has not existed any lung simulator structurally and functionally symbolic of the human lungs and of conditions representative of various respiratory ailments such as various disease and/or structural complications and the like, although there has existed and continues to exist a need for such a teaching aid in institutions of higher learning of the medical profession. U.S. Pat. No. 3,374,554 discloses a single flexible balloon purportedly representative of a lung within a transparent casing having a flexible resilient wall for expansion and contraction responsive to chamber pressure of the casing having a conduit from casing space vented to atmosphere, and pressure-producing mechaism attached to the input tube to the balloon; teaching capabilities in the use of such device would be severely limited. Otherwise, there have existed U.S. Pat. No. 3,276,147 and U.S. Pat. No. 4,001,950 and U.S. Pat. No. 3,049,811 each illustrating the effect of mouth-to-mouth recuscitation upon one or more inflatable bags having some resistance to inflation, and associated operating equipement therefor. Likewise U.S. Pat. No. 3,274,705 illustrate a plurality of three bags connected to inflate and deflate responsive to mouth-to-mouth recescitation practice methods, limited to such type demonstration.